The outer and inner segments of vertebrate retina

Retina

The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...

 rod photoreceptor cells contain phosducin

Phosducin

Phosducin, also known as PDC, is a human protein and gene. It belongs to phosducin family of proteins.-Further reading:...

, a soluble phosphoprotein

Phosphoprotein

Phosphoproteins are proteins that are physically bonded to a substance containing phosphoric acid . This category of organic molecules includes Fc receptors, Ulks, Calcineurins, K chips, and urocortins....

 that complexes with the beta/gamma-subunits of the guanosine triphosphate

Guanosine triphosphate

Guanosine-5'-triphosphate is a purine nucleoside triphosphate. It can act as a substrate for the synthesis of RNA during the transcription process...

-binding protein, transducin

Transducin

Transducin is a heterotrimeric G protein that is naturally expressed in vertebrate retina rods and cones .- Mechanism of action :...

. Light-induced changes in cyclic nucleotide levels modulate the phosphorylation

Phosphorylation

Phosphorylation is the addition of a phosphate group to a protein or other organic molecule. Phosphorylation activates or deactivates many protein enzymes....

 of phosducin by protein kinase A. The protein is thought to participate in the regulation of visual phototransduction or in the integration of photo-receptor metabolism. Similar proteins have been isolated from the pineal gland

Pineal gland

The pineal gland is a small endocrine gland in the vertebrate brain. It produces the serotonin derivative melatonin, a hormone that affects the modulation of wake/sleep patterns and seasonal functions...

 and it is believed that the function of the protein is the same in both retina and pineal gland.

Human proteins containing this domain

Gene	Aliases	Protein
PDC Phosducin Phosducin, also known as PDC, is a human protein and gene. It belongs to phosducin family of proteins.-Further reading:...	MEKA	phosducin
PDCL	PhLP1	phosducin-like
PDCL2	GCPHLP	phosducin-like 2
PDCL3	PhLP2A	phosducin-like 3
TXNDC9 TXNDC9 Thioredoxin domain-containing protein 9 is a protein that in humans is encoded by the TXNDC9 gene.-Further reading:...	PhLP3	thioredoxin domain containing 9